Example Exercise: 8.23 (OpenIntro Statistics / Advanced High School Statistics)

Slides are available at
drive.google.com/open?id=1wnn...
An earlier exercised introduces data on the Coast Starlight Amtrak train that runs from Seattle to Los Angeles. The mean travel time from one stop to the next on the Coast Starlight is 129 mins, with a standard deviation of 113 minutes. The mean distance traveled from one stop to the next is 108 miles with a standard deviation of 99 miles. The correlation between travel time and distance is 0.636.
(a) Write the equation of the regression line for predicting travel time.
(b) Interpret the slope and the intercept in this context.
(c) Calculate R^2 of the regression line for predicting travel time from distance traveled for the Coast Starlight, and interpret R^2 in the context of the application.
(d) The distance between Santa Barbara and Los Angeles is 103 miles. Use the model to estimate the time it takes for the Starlight to travel between these two cities.
(e) It actually takes the Coast Starlight about 168 mins to travel from Santa Barbara to Los Angeles. Calculate the residual and explain the meaning of this residual value.
(f) Suppose Amtrak is considering adding a stop to the Coast Starlight 500 miles away from Los Angeles. Would it be appropriate to use this linear model to predict the travel time from Los Angeles to this point?
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[@mssr1965]

As always a very good explanation about the elements when linear regression applied. I really enjoyed the last question with extrapolation and the unrealistic value of first one when x=0.